1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus, and a process cartridge and a developing blade applied to the apparatus.
Here, the electrophotographic image forming apparatus (hereinafter referred to as the xe2x80x9cimage forming apparatusxe2x80x9d) is an apparatus that forms an image on a recording medium using an electrophotographic image forming process. Examples of the image forming apparatus are an electrophotographic copying machine, an electrophotographic printer (for instance, an LED printer, a laser beam printer, and the like), an electrophotographic facsimile apparatus, and an electrophotographic word processor.
Also, the process cartridge may integrally incorporate a charging means, a developing means, or a cleaning means, and an electrophotographic photosensitive member into a cartridge that is detachably mountable to a main body of the image forming apparatus. Alternatively, the process cartridge may integrally incorporate the electrophotographic photosensitive member and at least one of the charging means, the developing means, and the cleaning means into a cartridge that is detachably mountable to the main body of the image forming apparatus. Further alternatively, the process cartridge may integrally incorporate at least the developing means with an electrophotographic photosensitive drum into a cartridge that is detachably mountable to the main body of the image forming apparatus.
2. Description of Related Art
A process cartridge is composed of a cleaning unit and a developing unit. The cleaning unit integrally includes a charging means, a cleaning means, and a photosensitive drum, and the developing unit integrally includes a developing means and toner supplied to the developing means. The cleaning unit and the developing unit are integrally connected to each other using a connecting member, thereby obtaining the process cartridge (see FIG. 33).
In an image forming apparatus employing an electrophotographic method, it becomes necessary to exchange a photosensitive drum, to replenish or exchange developer, and to adjust, clean, or exchange other components (such as a charger and a cleaner container) when the operating time of the image forming apparatus becomes long. In reality, however, such maintenance work is difficult for a person who is not a serviceman having expert knowledge.
As to the aforementioned process cartridge, there is publicly known a construction in which a photosensitive unit, which supports an electrophotographic photosensitive member, a cleaning means, and the like, is connected to a developing unit, which supports a developing means, using a connecting member.
Therefore, the image forming apparatus that forms an image on a recording medium using an electrophotographic image forming process adopts a process cartridge system in which the electrophotographic photosensitive member and a process means acting on this electrophotographic photosensitive member are integrally made into a cartridge which is detachably mountable to the main body of the image forming apparatus. In accordance with this process cartridge system, the image forming apparatus can be personally maintained by a user without relying on a serviceman, so that operability can be greatly improved. Therefore, this process cartridge system can be used in a wide variety of image forming apparatuses.
In the process cartridge, the developing unit is rotatably supported about a rotational axis with respect to the photosensitive unit and is biased toward the photosensitive unit side by the self-weight of the developing unit or a pressurizing member like a spring. That is, a developer bearing member in the developing unit is biased against the electrophotographic photosensitive member in the photosensitive unit through a space maintaining member. With this construction, a constant minute space is always maintained between the electrophotographic photosensitive member and the developer bearing member, whereby fine images can be outputted with stability.
As to the process cartridge, it is desired that the accuracy of mounting positions of parts related to image formation be further improved in order to further improve image quality.
As to the process cartridge, further cost reduction is also desired.
An object of the invention is to provide a process cartridge capable of maintaining a space between a developing roller and an electrophotographic photosensitive drum always constant with accuracy, an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and a developing blade for use in the process cartridge.
It is another object of the invention to provide a process cartridge capable of surely biasing a developing roller in a direction in which the developing roller abuts against an electrophotographic photosensitive drum, an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and a developing blade for use in the process cartridge.
It is still another object of the invention to provide a process cartridge reduced in cost by attaching one end of a biasing member for biasing a developing roller in a direction in which the developing roller abuts against an electrophotographic photosensitive drum to a supporting portion of a developing blade, an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and the developing blade for use in the process cartridge.
It is still further another object of the invention to provide a process cartridge capable of improving detection of a remaining amount of developer, an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and a developing blade for use in the process cartridge.
It is still further another object of the invention to provide a process cartridge capable of applying voltage to a supporting portion of a developing blade by using a biasing member for biasing a developing roller in a direction in which the developing roller abuts against an electrophotographic photosensitive drum, an electrophotographic image forming apparatus to which the process cartridge is detachably mountable, and the developing blade for use in the process cartridge.
Also, it is another object of the invention to provide a process cartridge detachably mountable to a main body of an electrophotographic image forming apparatus, the process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; a developing blade for regulating an amount of developer on a peripheral surface of the developing roller, the developing blade having a regulating portion for regulating the amount of developer on the peripheral surface of the developing roller and a supporting portion for supporting the regulating portion; a developing frame that rotatably supports the developing roller, the supporting portion of the developing blade being attached to the developing frame; a drum frame that rotatably supports the electrophotographic photosensitive drum and that is connected to the developing frame, wherein the drum frame and the developing frame are connected rockably to each other; and a biasing member for biasing the developing roller toward the electrophotographic photosensitive drum, wherein one end of the biasing member is attached to at least one end of the supporting portion in a longitudinal direction of the developing roller.
Also, it is still another object of the invention to provide an electrophotographic image forming apparatus to which a process cartridge is detachably mountable for forming an image on a recording medium, the electrophotographic image forming apparatus comprising: (i) mounting means for detachably mounting the process cartridge, the process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; a developing blade for regulating the amount of developer on a peripheral surface of the developing roller, the developing blade having a regulating portion for regulating an amount of developer on the peripheral surface of the developing roller and a supporting portion for supporting the regulating portion; a developing frame that rotatably supports the developing roller, the supporting portion of the developing blade being attached to the developing frame; a drum frame that rotatably supports the electrophotographic photosensitive drum and that is connected to the developing frame, wherein the drum frame and the developing frame are connected rockably to each other; and a biasing member for biasing the developing roller toward the electrophotographic photosensitive drum, wherein one end of the biasing member is attached to at least one end of the supporting portion in a longitudinal direction of the developer roller; and (ii) transporting means for transporting the recording medium.
Also, it is still another object of the invention to provide a developing blade for use in a process cartridge, the process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; a developing frame that rotatably supports the developing roller; a drum frame that rotatably supports the electrophotographic photosensitive drum and that is connected to the developing frame, wherein the drum frame and the developing frame are connected rockably to each other; and a biasing member for biasing the developing roller toward the electrophotographic photosensitive drum, the developing blade comprising: a regulating portion for regulating an amount of developer on a peripheral surface of the developing roller; and a supporting portion for supporting the regulating portion, the supporting portion being to be attached to the developing frame and having an attaching portion to which one end of the biasing member is attached.